Engine exhaust systems



Feb. 10, 1970 R. T. JOHNSON ENGINE ExHAusT- SYSTEMS 2 Sheets-Sheet 1 Filed March 14, 1968 FIGJ .FIG-2 N R04 WH m0 J T T R E B O Atmmays 4 Feb. 10, 1970 R. T. JOHNSON 3,494,334

ENGINE EXHAUST SYSTEMS Filed March 14, 1968 2 Sheets-Sheet 2 TI /2 /Z Z l V I //7)7fi Fw k w INVENTOR. ROBERT T JOHNSON Attorneys United States Patent 3,494,334 ENGINE EXHAUST SYSTEMS Robert T. Johnson, Oshkosh, Wis., assignor to Brunswick Corporation, Chicago, Ill., a corporation of Delaware Filed Mar. 14, 1968, Ser. No. 713,242 Int. Cl. F02b 75/20; F02d 39/04; F01n 7/00 U.S. Cl. 123-65 4 Claims ABSTRACT OF THE DISCLOSURE A multiple cylinder two-cycle engine having the cylinders exhausting through openings in the cylinder walls and into an exhaust manifold divided into two baffle separated chambers. The individual exhaust ports through the cylinder walls are restricted for a short distance to simulate a tuned effect for the exhaust.

This invention relates to a multi-cylinder two-cycle engine wherein two or more cylinders exhaust through openings in the cylinder walls into a common manifold.

A construction to which the invention has been applied is illustrated in U.S. Patent No. 3,020,707 for Engine Exhaust Manifold Construction. In this construction the engine has six cylinders in line alOng a common crank shaft and the exhaust ports from each cylinder open directly through the cylinder walls into a common manifold, which is shown as divided into two chambers in order to avoid interference arising from the firing sequence for the several cylinders and to promote a slight tuning effect between the cylinders that fire 120 apart.

It has been found that certain pressure waves develop in the manifold from the individual exhaust of the cylinders and which may be taken advantage of in increasing engine efficiency.

The present invention is based upon the discovery that increased efficiency can be obtained by confining the exhaust for a short distance as it flows from the cylinder and before it enters the free space of the manifold chamber. In this way the velocity of the gas flow into the manifold is at a higher velocity without significant loss in pressure, and there is an increased influence of the reflected wave on another cylinder which is exhausting or upon cylinder which can benefit from an exhaust pressure signal.

The desired effect may be obtained with baflle means of various shapes in the manifold. Two such shapes presently considered as the best mode of carrying out the invention are illustrated in the accompanying drawings.

In the drawings:

FIGURE 1 is a side elevation of a six cylinder engine block with the manifold cover removed and showing the exhaust ports for the cylinders;

FIG. 2 is an enlarged partial section taken transversely of the engine generally axially of a cylinder thereof;

FIG. 3 is an enlarged detail section showing the port in greater detail; and

FIGURE 4 is a similar enlarged detail section showing a modified construction for the port.

The two-cycle internal combustion engine generally has a cast engine block 1, one side of which provides an exhaust manifold 2 with an outer wall or closure plate 3 on its face sealed against a peripheral wall '4 on the casting and which is open at one end for discharging exhaust gases from the manifold through exhaust discharge opening 5.

The individual cylinders 6 in the engine block 1 have suitable exhaust ports 7 leading directly through the cylinder walls and into the manifold. In the embodiment shown there are three exhaust ports 7 spaced circumferentially for each cylinder.

As shown in Patent No. 3,020,707, referred to above, the manifold 2 may preferably be divided into two chambers 8 and 9 by a partition 10 with each chamber receiving the exhaust from a selected three of the cylinders to provide for greater engine efficiencies and avoid interference with the exhaust of one cylinder by that of another.

The present invention has been found to substantially add to the efficiency of the engine by providing a bafile construction in the manifold and surrounding each of the exhaust ports in a manner generally turning the direction of exhaust flow at right angles to the port as the exhaust is released into the manifold chamber.

The battle construction illustrated in FIGS. 2 and 3 comprises principally a short flange 11 surrounding the ports 7 for each cylinder and extending into the corresponding manifold chamber 8 or 9.

The wall of the cylinder in the region of the exhaust ports 7 is preferably double to provide a water jacket 12 for the cylinder at this location for cooling purposes.

This double thickness for the cylinder wall plus the flange 11 provides exhaust ports 7 of substantial length.

For the purpose of turning the direction of exhaust flow from the ports 7 into the manifold 2, the closure plate 3 has an inward extension 13 which is generally complemental to and abuts the end of flange 11 with a curved interior leading to a free opening 14 to one side of the ports for the corresponding cylinder.

The extension 13 is generally hollow and serves as a portion of water jacket 15 between closure plate 3 and an outer cover plate 16. In this way the exhaust passage through ports 7 is more effectively cooled and the exhaust is thereby initially subjected to cooling as it flows through the ports 7 and opening 14.

In the construction illustrated in FIG. 4 a longer passageway for the exhaust is provided by a separate insert 17 which is bolted to the block and the cover plate extension 18 is shorter.

The insert 17 is generally hollow to provide a separate water jacket 19 surrounding each port and connected to water jacket 12 to provide the desired cooling of the hot exhaust gases as they pass through the port.

= The direction of flow of the exhaust gases from the respective ports 7 is preferably away from the nearest wall 4 or partition 10, and toward the farthest wall 4 or partition 10 as the case may be.

The invention provides a slightly tuned effect for the exhaust resulting in part from the longer cooled port passage for the exhaust.

Tests have indicated that an engine embodying the invention has a horsepower output two to three percent greater than the same engine without the invention and constructed according to the Patent No. 3,020,707, referred to above. A corresponding decrease in fuel consumption was also noted.

The invention keeps the intensity of the high pressure wave developed upon uncovering of the exhaust port, at a higher level for a longer duration of time, and it reduces the frictional loss of the exhaust by providing an initial smooth passageway for turning the direction of the exhaust flow. The high pressure wave created by the exhaust discharge from one cylinder is reflected to another cylinder where the exhaust port is just closing, thus tending to increase the pressure in the latter cylinder upon cut-off of the exhaust port therefor.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention,

3 I claim: 1. In a multi-cylinder two-cycle internal combustion engine in which each cylinder exhausts through one or more ports through the wall of the cylinder into a common manifold chamber from which it is discharged through an opening therefor, the improvement comprising an extension for the port or ports for each cylinder and providing a passage having an internal curvature directing the exhaust gases into the manifold generally at right angles to the port and generally at right angles to the flow of gases in said manifold toward said opening.

2. The improvement of claim 1 comprising a flange surrounding the port in the cylinder Wall and a complementary extension from the opposite outer wall of the manifold abutting the end of the flange and providing a curved interior passage leading to a directive discharge opening for the exhaust gases into the manifold.

3. The construction of claim 2 in which said flange and extension are cooled by water jacket means constituting a part of the engine cooling means.

4. The construction of claim 1 in which the major portion of said extension is formed integral with the cylinder block.

References Cited UNITED STATES PATENTS 4/1911 Sherbondy. 10/ 1919 McElrath. 11/1924 Skarlund. 12/1931 Ricardo.

4/ 1941 Violet.

12/ 1945 Barrett.

6/ 1953 Kiekhaefer.

1/ 1956 Meyer.

5/1958 Lejardi.

10/ 1963 Kiekhaefer.

FOREIGN PATENTS 8/1945 Great Britain. 9/1945 Great Britain.

US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,494,334 Dated February 10, 1970 Inventor(s) Robert T. Johnson It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 46, after "flected" and before "wave" insert --pressure-- Column 1, line 46, after "upon" insert ---another-- Column 2, line 6, after "the" and before "cylinders" insert --six-- Column 2, line 32, after "of" insert .--a-- SIGNED AND SEALED JIIL? I910 (SEAL) Attest:

M. Fletc e I E. sum, m- Attesting Officer Patents FORM F G-1050 (IO-59) uscoMM-Dc 60376 P69 US. GOVEINMENT PRINTING OFFICE: IO. Ol-l84 

